The goals of this study are to localize novel non-syndromic hearing loss (NSHL) genes and to isolate some of these genes. NSHL kindreds are being ascertained by the applicants. A database will be developed which contains lod scores and haplotype data from current NSHL studies in addition to integrated genetic maps of marker loci in the region of NSHL genes. The data will be made publicly available through the study's web page (http://linkage.rockefeller.edu/nshl). Localizing and isolating genes responsible for NSHL is challenging due to extreme genetic heterogeneity. The genetic regions for NSHL loci are often imprecise, due to the limited number of families available for study of each locus. Therefore, mutation detection in candidate genes will be used to isolate NSHL genes. A gene will be considered a candidate if it meets the following criteria: maps to the physical region of a NSHL locus; and has tissue specific expression (i.e. cochlea). Candidate genes will be sequences in controls and affected individuals from families with a high probability of segregating the NSHL loci of interest.